Factors affecting loss of control in general aviation aircraft

Abstract

A quarter of all fatal General Aviation accidents in the UK during the period 1980 to 2006 involved Loss of Control (LoC) in Visual Meteorological Conditions (VMC). LoC – which effectively the stall/spin event, has consistently appeared in accident statistics over this period, but at very different rates for different aircraft types. This raises two important questions - why do these LoC events happen and why is there a difference between aircraft types?.

The biggest discrepancy affects the Cessna 150 and Cessna 152, two aircraft similar in appearance and highly popular in the pilot training environment. The Cessna 150 falls approximately on the average for stall/spin related fatal accidents in the UK GA fleet, whereas the Cessna 152 exhibits an extremely low accident rate. Brunel Flight Safety Laboratory, in conjunction with the UK General Aviation Safety Council, undertook to try and understand why.

The key design differences affecting performance and handling qualities were thoroughly researched using available published material and informal interviews with type-experienced students, pilots and flying instructors.

A comprehensive flight test programme was then commenced using examples of both aircraft types to gather additional research data in order to assess and compare the apparent performance and handling qualities (both qualitatively and quantitatively). The flight tests were performed at different CG conditions relevant to the key design differences, concentrating upon apparent longitudinal (static and dynamic) stability and control characteristics, stalling and low-speed handling characteristics, and cockpit ergonomics / pilot workload.

This test was using normal flying club aircraft, but in most cases with a 2-man (TP+FTE) crew with data recorded both manually and using a low-cost, portable Appareo GAU1000A Flight Data Recorder (FDR).

The paper covers both the conduct of these tests – flight testing within a university environment, preparation, pre and post-test analysis, construction of Cooper-Harper tasks and the use of low-cost automated flight data recording. It will also however discuss the team’s initial conclusions and ongoing research into both design and pilot training causes behind GA LoC incidents.